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Help me understand! A speeding motorcyclist sees traffic jam ahead of him. He slows down to 36 km/hour. He finds that traffic has eased and a car moving a head of him at 18 km/hour is honking at a frequency of 1392 Hz. If the speedof sound is 343 m/s

A speeding motorcyclist sees traffic jam ahead of him. He slows down to 36 km/hour. He finds that traffic has eased and a car moving a head of him at 18 km/hour is honking at a frequency of 1392 Hz. If the speed of sound is 343 m/s, the frequency of the honk as heard by him will be:

  • Option 1)

    1332 Hz

  • Option 2)

    1372 Hz

  • Option 3)

    1412 Hz

  • Option 4)

    1464 Hz

 
Answers (1)
112 Views
V Vakul

As we discussed

frequency of sound when source is moving away and observer is moving towards the source -

\nu {}'= \nu _{0}.\frac{C+V_{0}}{C+V_{s}}

- wherein

C= Speed of sound

V_{0}= Speed of observer

V_{s}= speed of source

\nu _{0 }= Original frequency

\nu {}'= apparent frequency

 

According to doppler's effect

{V}'= V(\frac{V+V_o}{V+V_s})=1392(\frac{343+10}{343+5})

{V}'=1412 \ Hz 


Option 1)

1332 Hz

Incorrect

Option 2)

1372 Hz

Incorrect

Option 3)

1412 Hz

Correct

Option 4)

1464 Hz

Incorrect

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